Publications by authors named "Christopher Cormier"

5 Publications

  • Page 1 of 1

Myoepithelial Carcinoma Ex-Pleomorphic Adenoma: A Rare Pathology Misdiagnosed as Pleomorphic Adenoma; With a Novel TERT Promoter Mutation and High PD-L1 Expression.

Head Neck Pathol 2021 Jun 14. Epub 2021 Jun 14.

Department of Pathology, University of New Mexico School of Medicine, University of New Mexico, MSC08 4640, Albuquerque, NM, 87131, USA.

Myoepithelial carcinoma (MECA) is a rare salivary gland (SG) neoplasm (0.1-0.45% of all SG tumors) that often presents with bland cytomorphology and can be misclassified as cellular pleomorphic adenoma (PA) or myoepithelioma. This is particularly challenging in MECA ex-PA cases, especially if tumor shows minimal to no capsular invasion. We report a rare case of a 76-year-old female; history of left superficial parotidectomy with diagnosis (outside hospital) of cellular PA, who re-presented 9 months post surgery with enlarging left parotid mass, neck lymphadenopathy and facial nerve deficits. FNAB of parotid and neck lymph node revealed cellular aspirates with loosely cohesive clusters of myoepithelial cells with occasional chondromyxoid stroma. Prior resection slides were reviewed, and diagnosis of MECA ex-PA was made. Patient underwent left radical parotidectomy, selective neck dissection, with facial nerve sacrifice (due to extensive encasing by tumor). Histology showed a multinodular tumor with pushing borders, zonal arrangement comprising of a hypocellular, necrotic/myxoid center, and a peripheral rim of myoepithelial cells, confirmed by positive S100, and p63. Tumor extensively infiltrated peri parotid soft tissues with multiple foci of lymphovascular and perineural invasion; and metastatic neck lymph nodes. Next generation sequencing revealed a novel TERT promoter mutation (c.-124C > T), not usually described in SG neoplasms. Further, PD-L1 immunohistochemistry showed positive expression, making patient eligible for anti-PDL-1 immunotherapy. This case highlights importance of recognizing the subtle malignant features of MECA in distinguishing it from benign mimics like PA. In addition, presence of TERT mutation opens a new arena for future research to explore potential treatment targets.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s12105-021-01346-0DOI Listing
June 2021

Impact of Etch Processes on the Chemistry and Surface States of the Topological Insulator BiSe.

ACS Appl Mater Interfaces 2019 Sep 26;11(35):32144-32150. Epub 2019 Aug 26.

Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States.

The unique properties of topological insulators such as BiSe are intriguing for their potential implementation in novel device architectures for low power and defect-tolerant logic and memory devices. Recent improvements in the synthesis of BiSe have positioned researchers to fabricate new devices to probe the limits of these materials. The fabrication of such devices, of course, requires etching of the topological insulator, in addition to other materials including gate oxides and contacts which may impact the topologically protected surface states. In this paper, we study the impact of He sputtering and inductively coupled plasma Cl and SF reactive etch chemistries on the physical, chemical, and electronic properties of BiSe. Chemical analysis by X-ray photoelectron spectroscopy tracks changes in the surface chemistry and Fermi level, showing preferential removal of Se that results in vacancy-induced n-type doping. Chlorine-based chemistry successfully etches BiSe but with residual Se-Se bonding and interstitial Cl species remaining after the etch. The Se vacancies and residuals can be removed with postetch anneals in a Se environment, repairing BiSe nearly to the as-grown condition. Critically, in each of these cases, angle-resolved photoemission spectroscopy (ARPES) reveals that the topologically protected surface states remain even after inducing significant surface disorder and chemical changes, demonstrating that topological insulators are quite promising for defect-tolerant electronics. Changes to the ARPES intensity and momentum broadening of the surface states are discussed. Fluorine-based etching aggressively reacts with the film resulting in a relatively thick insulating film of thermodynamically favored BiF on the surface, prohibiting the use of SF-based etching in BiSe processing.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.9b10625DOI Listing
September 2019

Dislocation driven spiral and non-spiral growth in layered chalcogenides.

Nanoscale 2018 Aug;10(31):15023-15034

Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080, USA.

Two-dimensional materials have shown great promise for implementation in next-generation devices. However, controlling the film thickness during epitaxial growth remains elusive and must be fully understood before wide scale industrial application. Currently, uncontrolled multilayer growth is frequently observed, and not only does this growth mode contradict theoretical expectations, but it also breaks the inversion symmetry of the bulk crystal. In this work, a multiscale theoretical investigation aided by experimental evidence is carried out to identify the mechanism of such an unconventional, yet widely observed multilayer growth in the epitaxy of layered materials. This work reveals the subtle mechanistic similarities between multilayer concentric growth and spiral growth. Using the combination of experimental demonstration and simulations, this work presents an extended analysis of the driving forces behind this non-ideal growth mode, and the conditions that promote the formation of these defects. Our study shows that multilayer growth can be a result of both chalcogen deficiency and chalcogen excess: the former causes metal clustering as nucleation defects, and the latter generates in-domain step edges facilitating multilayer growth. Based on this fundamental understanding, our findings provide guidelines for the narrow window of growth conditions which enables large-area, layer-by-layer growth.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8nr02280aDOI Listing
August 2018

High-Mobility Helical Tellurium Field-Effect Transistors Enabled by Transfer-Free, Low-Temperature Direct Growth.

Adv Mater 2018 Jul 18:e1803109. Epub 2018 Jul 18.

Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080, USA.

The transfer-free direct growth of high-performance materials and devices can enable transformative new technologies. Here, room-temperature field-effect hole mobilities as high as 707 cm V s are reported, achieved using transfer-free, low-temperature (≤120 °C) direct growth of helical tellurium (Te) nanostructure devices on SiO /Si. The Te nanostructures exhibit significantly higher device performance than other low-temperature grown semiconductors, and it is demonstrated that through careful control of the growth process, high-performance Te can be grown on other technologically relevant substrates including flexible plastics like polyethylene terephthalate and graphene in addition to amorphous oxides like SiO /Si and HfO . The morphology of the Te films can be tailored by the growth temperature, and different carrier scattering mechanisms are identified for films with different morphologies. The transfer-free direct growth of high-mobility Te devices can enable major technological breakthroughs, as the low-temperature growth and fabrication is compatible with the severe thermal budget constraints of emerging applications. For example, vertical integration of novel devices atop a silicon complementary metal oxide semiconductor platform (thermal budget <450 °C) has been theoretically shown to provide a 10× systems level performance improvement, while flexible and wearable electronics (thermal budget <200 °C) can revolutionize defense and medical applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.201803109DOI Listing
July 2018

Fermi Level Manipulation through Native Doping in the Topological Insulator BiSe.

ACS Nano 2018 Jun 8;12(6):6310-6318. Epub 2018 Jun 8.

Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States.

The topologically protected surface states of three-dimensional (3D) topological insulators have the potential to be transformative for high-performance logic and memory devices by exploiting their specific properties such as spin-polarized current transport and defect tolerance due to suppressed backscattering. However, topological insulator based devices have been underwhelming to date primarily due to the presence of parasitic issues. An important example is the challenge of suppressing bulk conduction in BiSe and achieving Fermi levels ( E) that reside in between the bulk valence and conduction bands so that the topologically protected surface states dominate the transport. The overwhelming majority of the BiSe studies in the literature report strongly n-type materials with E in the bulk conduction band due to the presence of a high concentration of selenium vacancies. In contrast, here we report the growth of near-intrinsic BiSe with a minimal Se vacancy concentration providing a Fermi level near midgap with no extrinsic counter-doping required. We also demonstrate the crucial ability to tune E from below midgap into the upper half of the gap near the conduction band edge by controlling the Se vacancy concentration using post-growth anneals. Additionally, we demonstrate the ability to maintain this Fermi level control following the careful, low-temperature removal of a protective Se cap, which allows samples to be transported in air for device fabrication. Thus, we provide detailed guidance for E control that will finally enable researchers to fabricate high-performance devices that take advantage of transport through the topologically protected surface states of BiSe.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsnano.8b03414DOI Listing
June 2018